Boris Johnson is the favourite to succeed David Cameron as prime minister.
Photograph: Jack Taylor/Getty Images

European diplomats have dismissed claims from Boris Johnson that the UK could negotiate access to the EU single market without obeying any of the rules.

“You cannot have your cake and eat it,” said an EU diplomat, echoing a phrase the former mayor of London used during the campaign and which looks set to come back to haunt him.

In a further blow to the leave camp’s credibility, Germany’s leading business group distanced itself from Johnson’s suggestion that German business expected Britain’s free trade with Europe to continue seamlessly.

After more than two days of silence following the leave campaign’s stunning victory, Johnson set out his pitch for the UK’s future relationship with the EU in one of his highly lucrative Daily Telegraph columns.

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The Brexit leader, who is the favourite to succeed David Cameron as prime minister, claimed that Britain would remain a member of the EU’s single market while introducing a points-based immigration system to limit the right of EU citizens to work in Britain.

British people would still be able to live, travel, study and buy homes on the continent but the same rights would not be automatically extended to EU citizens in the UK, he wrote. Britain would also be freed from sending “a substantial sum of money” to the EU budget, which he said “could” be used for the NHS.

Johnson insisted the only change – “and it will not come in any great rush – is that the UK will extricate itself from the EU’s extraordinary and opaque system of legislation”.

EU diplomats reacted witheringly to the idea that the UK could stay in the single market without following the rules.

“It is a pipe dream,” said the EU diplomat. “You cannot have full access to the single market and not accept its rules. If we gave that kind of deal to the UK, then why not to Australia or New Zealand. It would be a free-for-all.”

A second EU diplomat said: “There are no preferences, there are principles and the principle is ‘no pick and choose’.”

The diplomat stressed that participating in the single market meant accepting EU rules, including the jurisdiction of the European court of justice, monitoring by the European commission and accepting the primacy of EU law over national law – conditions that will be anathema to leave advocates who campaigned on the mantra “take back control”.

“There is no logic of punishment or sanction but the application of the law,” the diplomat said.

A third EU diplomat said the Brexit side had “no clue” what was going on and did not have a plan.

The Brexit camp’s claims of support from German industry also began unravelling when the country’s leading industry group distanced itself from Johnson’s rose-tinted scenario.

In the Telegraph column, Johnson claimed that the German equivalent of the CBI, the BDI, had “very sensibly reminded us there will continue to be free trade and access to the single market”.

When asked about Johnson’s comments, a BDI spokesperson pointed out that while its head, Markus Kerber, had described trade barriers as “very, very foolish” in a BBC interview on 22 June, he had been commenting on one of several fictional scenarios.

In previous interviews, the BDI spokesperson said, Kerber had warned that a vote to leave would spark a “tooth-and-nail fight” between the UK and erstwhile trade partners. “It wouldn’t be an amicable divorce”, Kerber told Bloomberg in February. “There’s no default European free-trade status in the waiting.”

In a statement released in response to the Johnson column, the BDI warned the British government against leaving its status in relation to the EU in limbo. “British politics now has to quickly set in motion the required processes, the EU and Great Britain both have quickly state their aims,” it said.

“We deeply regret the result of the referendum,” the BDI statement added. “The decision weakens the United Kingdom itself, the EU and Germany – politically as well as economically. Those responsible in politics now have to do everything to minimise the damage.”

EU diplomats are slowly groping towards a consensus on a Brexit timetable, following crisis talks between 27 senior diplomats on Sunday that excluded the UK. The increasingly dominant view is that Britain should trigger article 50 by the end of the year, starting the clock on two years of divorce negotiations. This would allow the UK to leave the EU before European parliament elections and the appointment of a new European commission in 2019.

Although countries are split over how much pressure to put on London to fire the starting gun on talks, Brussels appears united that there can be no informal talks, before the UK notifies the EU of its intention to leave. “No negotiations without notification” is becoming the key phrase in the standoff with London.

“If they treat their referendum as a non-event, we will also treat their referendum as a non-event,” an EU diplomat said.

But some Brussels insiders are worried that the UK may never trigger article 50, because the two-year deadline for talks would put the leaver in a weak position. “I personally believe they will never notify,” the diplomat said. “The moment you push the button you are in a stupid negotiating position.”

Some speculate that this could weaken the EU’s bargaining position, as governments may be tempted to make a deal with the UK as uncertainty drags on. But others reject this scenario, pointing out that until Britain starts the article 50 process it remains an EU member, with all the rights and duties that go with it.